Cell surface glycosyltransferases are being purified and characterized from rat and bovine lymphocytes to elucidate their functioning in cell surface phenomena in these systems. Surface glycoconjugates are being labelled isotopically using chemical and enzymatic methods. A receptor from calf lymphocytes, specific for N-acetyl glucosamine is being purified and characterized. Cell interactions using various mitogens in culture systems as models are being studied.